1. Field of the Invention
The present invention relates to an in-cell touch liquid crystal display (LCD) device having a pixel electrode top structure and a method of manufacturing the same.
2. Discussion of the Related Art
Instead of a mouse or a keyboard which is conventionally applied to flat panel display devices, a touch screen that enables a user to directly input information with a finger or a pen is applied to flat panel display devices. Especially, since all users can easily manipulate the touch screen, the application of the touch screen is being expanded.
A touch screen is applied to monitors such as navigations, industrial terminals, notebook computers, financial automation equipment, and game machines, portable terminals such as portable phones, MP3 players, PDAs, PMPs, PSPs, portable game machines, DMB receivers, and tablet personal computers (PCs), and home appliances such as refrigerators, microwave ovens, and washing machines.
The touch screen may be classified as follows, based on a structure where the touch screen is coupled to a liquid crystal panel. The touch screen may be divided into an in-cell touch type in which the touch screen is built in a cell of a liquid crystal, an on-cell touch type in which the touch screen is disposed on a cell of a liquid crystal panel, an add-on type in which the touch screen is coupled to an outer portion of a display panel, and a hybrid type.
Hereinafter, a touch screen (a touch panel) being coupled to a liquid crystal panel is referred to as a touch display device.
FIG. 1 is a diagram illustrating a related art touch display device to which a touch screen is applied. FIG. 1, part (a) illustrates an add-on type touch display device. FIG. 1, part (b) illustrates a modified add-on type touch display device. FIG. 1, part (c) illustrates a hybrid type touch display device.
In the add-on type touch display device of FIG. 1, part (a) and the modified add-on type touch display device of FIG. 1, part (b), a touch screen is disposed on a liquid crystal panel that includes a thin film transistor (TFT) array substrate 1 and a color filter array substrate 2. A touch driving electrode (a TX electrode) and a touch receiving electrode (an RX electrode) are arranged in the touch screen. In this case, the touch driving electrode (the TX electrode) and the touch receiving electrode (the RX electrode) may be disposed on the same layer or different layers.
In the hybrid type touch display device of FIG. 1, part (c), a touch driving electrode (a TX electrode) is disposed on a TFT array substrate 1, and a touch receiving electrode (an RX electrode) is disposed on a color filter array substrate 2.
In the related art touch display device, since a liquid crystal panel and a touch screen are separately manufactured, a manufacturing process is complicated, and the cost increases.
Recently, an in-cell touch LCD device where a touch electrode (a touch sensor) is built into a cell of a liquid crystal panel has been developed for decreasing a thickness of a touch display device and reducing the manufacturing cost. The in-cell touch LCD device uses a common electrode, which is disposed on a TFT array substrate, as a touch electrode.
FIG. 2 is a diagram illustrating an in-cell LCD device having a mutual capacitive type.
Referring to FIG. 2, the in-cell touch LCD device having the mutual capacitive type uses common electrodes, which are arranged on a TFT array substrate, as a touch driving electrode (a TX electrode) and a touch receiving electrode (an RX electrode).
In the mutual capacitive type, a touch driving line 14 connected to the touch driving electrode (the TX electrode) and a touch receiving line 12 connected to the touch receiving electrode (the RX electrode) are disposed in a left bezel area and a right bezel area of a liquid crystal panel 10, causing an increase in a bezel width.
FIG. 3 schematically illustrates a process of manufacturing an in-cell touch display device having a common electrode top structure and illustrates the number of masks applied to a manufacturing process.
Referring to FIG. 3, in a common electrode top pixel structure, a common electrode is disposed on an uppermost layer in a pixel structure, and a pixel electrode is disposed under the common electrode. Here, a material of an active layer of a TFT may use low temperature poly silicon (LTPS).
In a related art in-cell touch LCD device to which the common electrode top pixel structure is applied, eleven masks are applied to a manufacturing process, and thus, a number of detailed processes are performed. For this reason, the manufacturing process is complicated, and the manufacturing cost increases.
Moreover, when the common electrode top pixel electrode is applied, a transmittance of light in a boundary area between red, green, and blue pixels is higher than a case where a pixel electrode top structure is applied. For this reason, color mixing between the red, green, and blue pixels occurs.